Hydraulic hoist



J1me 1938- c. G. EISENBERG, JR 2,120,967

7 'HYDRAULIC HGIST Filed March 15, 1937 2 Sheets-Sheet l INVENTOR.

ATTORNEY5.

Patented June 21,- 1938 PATENT OFFICE HYDRAULIC norsr Charles G. Eisenberg, In, Wauwatosa, Wis., assignor to The Hell 00., Milwaukee, Wis., a corporation of Wisconsin Application March 15, 1937, Serial No. 130,958

8 Claims.

My present invention relates in general to 1m provements in systems for actuating mechanisms by fluid pressure, and relates more specifically to improvements in the construction and opera- 5 tion of hydraulic hoists and similar or allied hydraulically operated devices.

Generally defined, an object of my present invention is to provide an improved hydraulic hoist I system which is simple and compact, yet highly flexible and efiicient in use.

When utilizing'hydraulic hoists for the operation of dump bodies and other accessories mounted upon vehicles, it frequently becomes desirable in order to conserve power and space, andto simplify the system, to employ the same pressure producing unit or pump for the .purpose of actuating all of the fluid operated mechanisms. Since the body actuating hoists of such systems are usually most important of the fluid operated mechanisms, the pressure producing pump is preferably more closely associated with these hoists than with the other accessories; and because of the fact that the body actuating hoist cylinders ordinarily are swingable relative to the vehicle chassis about pivot trunnions, and that the pump is preferably mounted directly upon and is swingable with' these cylinders, it becomes quite a problem to utilize this pump for actuating other hydraulic hoists or jacks mounted upon the same .vehicle but which are notsuspended from the body actuating hoists. In cases where these hydraulically actuated mechanisms are rather numerous, or require relatively large volumes of liquid, a .rather large liquid supply reservoir is 5 required; and this reservoir is then preferably mounted directly upon the vehicle chassis independently of the hoists, but because the common pump for all hydraulic devices is preferably suspended from the'movable body hoists, the supply of liquid for operating all of the accessories must naturally pass through the movable hoist and pump assemblage. The system must also be relatively leakproof in order to eliminate loss of actuating fluid which usually is oil, and all of these desirable conditions and requirements introducemany difficult problems. I It is therefore a more specific object of the preseutin'vention to provide an' improved hydraulic system for actuating various accessories 'mounted upon a common vehicle, wherein the pressure producing pump is carried directly by the movablemain hoist cylinders and is eifectively utilized to actuate other accessories.

Another specific object of my invention is the 55 provision of a vehicular hoist system wherein a twin cylinder hydraulic hoist having a liquid circulating pump mounted directly upon the cylinders thereof is utilized to actuate onemovable part such as the dump body, and in which the same'pump is'also employed to circulate liquid under pressure through other accessories such as the hydraulic jacks for operating a snow plow,

a dump-body tail gate, and the like.

A further specific object of the present invention is to provide an improved twin hydraulic 1 hoist assemblage wherein the hoist cylinders are swingably supported, and in which the actuating liquid is effectively conducted to the cylinders from an extraneous source and is returned from the cylinders to the source, without leakage. Still another specific object of my invention is the provision of a new and useful trunnion supported double cylinder hoist having the circulating pump supported by and swingable with the cylinders and supplied with actuating fluid from a fixed storage reservoir, the same pump also being adapted to furnish liquid under pressure for the actuation of other mechanisms.

These and other objects and advantages of my present invention will be apparent from the following detailed description,

A clear conception of an embodiment of the several features constituting my improvement, and of the mode of constructing and of utilizing hydraulic hoist systems built in accordance with 30 the invention, may be had by referring to the drawings accompanying and forming apart of this specification wherein like reference characters designate the same or similar parts in the various views. a 5

Fig. 1 is a part sectional fragmentary front view of a twin cylinder, telescopic, trunnion supported hydraulic hoist and circulating pump assemblage, looking toward the pump;

Fig. 2 is a part'sectional fragmentary side view 40 of the assemblage of Fig. l, the section being taken along the line 2-2;

Fig. 3 is a transverse horizontal section through the hoist and pump assemblage of Fig. 2, taken along the'line 3-3;

Fig. 4 is a transverse section through the liquid conducting joint which is disposed between the twin cylinder of the main hoist; and r Fig. 5 is a diagramshowing a system wherein the improved hoist may be used advantageously. v

While my invention has been shown and described herein as being specifically appliedto a telescopic twin hydraulichoist cooperating with hydraulic jacks for actuating a dump-body tailgate and a snow plow, itis not my intent to is advantageously applied in other types of systems. Referring to the drawings, and especially to the diagram of Fig. 5, the improved hydraulic system shown therein comprises in general a main hydraulic hoist having twin cylinders 8 pivotally suspended at their upper ends from a vehicle chassis 9, and having therein telescopic pistons I0; a dump body swingably attached at its rear portion to the chassis 9 and pivotally connected at its forward po tion to the upper ends of the inner pistons I8 by means of pivot ins I2; a tail gate I3 associated with the rear end of the body II and being operable by an auxiliary hydraulic hoist or jack I4 also mounted upon the chassis 9; another auxiliary hydraulic hoist or jack I5 mounted upon the chassis 9 and cooperable through linkage I6 with a snow plow or the like; a liquid supply reservoir I1 supported directly upon the chassis 9 independently of the hydraulic hoists; and a single liquid circulating pump I8 carried by and movable with the main hoist cylinders 8, for delivering liquid from the reservoir I1 to the cylinders 8 and to the hydraulic jacks I4, I5. It is to be understood that Fig. 5 is merely a diagram and does not show the parts in their actual shapes, sizes or locations; and the auxiliary jacks I4, I5 are alternately but not simultaneously operable, being controlled by means of a three-way valve I9. I V

The twin hydraulic cylinders 8 are spaced apart as shown in Figs. 1, 2 and, 3, and are pivotally suspended from the chassis 9 by means of alined trunnions 28 coacting with the outer sides thereof. Each of the cylinders 8 is provided with aisimilar liquid conducting port 2|, 22 at its upper end, and the ports 2|, 22 of the two cylinders 3 communicate with the opposite ends of a conduit forming joint interposed between the cylinders 8 in line with the supporting trunnions 29. This joint is shown in detail .in Figs. 2, 3 and 4, and comprises a stationary part or element 23 having a duct 24 which constantly connects the cylinder port 2| with a stationary pipe 25 leading to the supply reservoir I1, and having another duct 26 segregated from the duct 24 and constantly connecting the cylinder port 22 with another stationary pipe 21 leading to the control valve I9 of the jacks I4, I5. The ends of the element 23 abut against the inner sides of the cylinders 8 and are circular in cross-section, being snugly embraced by packings 28 confined in adjustable glands 29 carried by and oscillatable with the hoist cylinders 8, as clearly shown in Figs. 3 and 4. The liquid conducting joint assemblage is obviously so constructed that it will permit liquid to flow from the stationary supply reservoir H to the cylinder port 2| through the pipe 25 and duct 24, and from the port 22 to the jacks I4, I5 through the duct 26 and pipe 21,

while also permitting free oscillation of the main hoist cylinders 8 about the trunnions 20, but without permitting the liquid to escape at the Joints.

The single liquid circulating pump I8 is of the well known gear type, and is adapted-to be driven from the propelling motor of the vehicle, through a driving connection 38. This pump I8 is mounted directly upon the front of a manifold 3| rigidly attached to the forward upper portions of thecylinders 8; and a control valve 32 which is 01)- .erableby a. lever 33, is mounted upon the rear thereby unnecessarily restrict the scope, since .some of the improved features may obviously be through the cylinder port 2|, duct 24 and pipe 25, F

and these elements are also provided with communicating pressure ports 35 which communicate with the pipe 21 and control valve I9 for the auxiliary jacks I4, I5 through the port 22 and duct 26 past a pump discharge valve 36, see Fig. 2. The control valve casing and manifold 3| are moreover provided with communicating ports 31 which communicate with the upper ends of ducts 38 leading into the lower ends of the cylinders 8, as shown in Figs. 1 and 2, and the pump suction and discharge ports 34, 35 are adapted to be alternately connected with both of the ports 31 by a peripheral recess 39 in the valve 32. The valve 32 is also provided with an opposite peiripheral recess 49 which ,is connected with the recess 39 by a port 4|, and the valve 32 is also pierced longitudinally by a port 42 so as to balance the pressures acting upon opposite faces of the valve body. It is to be notedthat when the pump I8 is operating, the suction opening thereof is in constant open communication with the liquid supply reservoir I1 through the suction port 34, cylinder port 2|, duct 24 and pipe 25, and the pump will then deliver liquid under pressure past the discharge valve 36 into the ports 35 which communicate through the ports 22, duct 26 and pipe 21 with the jack control valve I9.

. Besides the manifold 3|, the main hoist cylinders 8 may be interconnected by means of a cross-beam 43 which is recessed as shown in Fig. 1, to clear the pipes 25, 21 during oscillation of the cylinders 8. A screw jack 44 may also be provided between the cylinders 8 near the joint element 23, in order to adjust the clearance between the ends of this element and the adjacent faces of the cylinders at theglands 29. Themain hoists are of the single acting telescopic type, and the'liquid ordinarily utilized I in the system, is oil of which there should be anabundant supply in the reservoir I1.

During normal operation of the improved hydraulic system and assuming the pump I8 to be operating, the three-way control valve I9 for the auxiliary jacks I4, I5 would normally be set to cut off communication between these jacks and the pressure supply pipe 21. The main hoist is then operable independently of the jacks I4. l5 to control the raising or lowering of the pistons I0, by manipulation of the control valve 32 alone. When the valve 32 is set in the position shown in Fig. 2, with the recess 39 connecting all of the ports 34, 35, 31, the pump I8 will merely be circulating oil from the suction ports 34 past the discharge valve 36, through the ports 35 and valve recess 39 back into the suction ports 3 34. Since this freely circulating oil is not under pressure, and in view of the fact that the ducts 38 are in open communication through the ports 31 with the recess 39 and suction ports 34, the pistons I8 and the body II will be free to descend .by gravity and will force oil from within the cylinders- 8 through the ports 34, 2|, duct 24 and pipe 25 into the supply reservoir I1 until the pistons II) are completely lowered. In order to subsequently elevate or raise the pistons III and body II, it is only necessary to swing the lever 33 so as to move. the valve 32 in a counterclockwise direction from the position shown in Fig.2, sufficiently to cut off communication between thesuction ports 34 and the valve recess 39 while maintaining the communication be vated to, tilt thedump body II.

raising of the dump body ll may thus be quickly v 2,120,967 tween-the ports 35, 31 through this recess. The

pump [8 will' then suck oil from the supply reservoir ll through the pipe 25, duct 24, and

ports 2|, 34; and will deliver this oil under preseffected by merely manipulating the valve 32 with the aid of the lever 33.

. If the valve 32 is set for raising of the pistons ill, the pump discharge ports 35'and the passages communicatingtherewith, will be filled.

with oil under pressure; and in order to then elevate either of the-jacks l4, l5, it is only necessary to adjust the control valve I9 so as to permit oil to escape to the jack which it is desired to operate through the port 22, duct 26 and stationary pipe 21. The elevated jack I4, i5 may thereafter be lowered or reversely operated simultaneously with 'the lowering of the main pistons ill, by merely setting the main control valve 32 into the position shown in Fig. .2,

whereupon the pressure in the ports 35 will be released as previously described. If such simultaneous lowering of the auxiliary jack is not desired, the valve l9 may be adjusted to retain oil under pressure within the elevated jack while the main hoist pistons ID are being loweredr In case the main pistons ill have been previously lowered, and it becomes desirable to lower the elevated jack l4, l5, it is only necessary to position the valve 32 as in Fig. 2-and to thereafter set the valve i9 so as to permit escape of the liquid under pressure from within the elevated jack through the pipe 21, duct and ports 22;, 35 to the suction port 34 through the valve recess 39. This reverse operation of the jacks it, l5 may be effected even if the pump i8 is at rest, and theexcess oil from the jacks will be returned to the supply reservoir I! through the ports 34, 2|, duct 24 and pipe 25. In case it is desired to actuate or elevate either of the jacks I4, i5 without elevating the main hoist pistons Ill, the pump l8 should be placed in operation,

the main valve 32 should be swung in a clockwise direction from the position shown in Fig. 2 sufficiently to close off communication between the ports 35, 31, and the control valve I9 should be set to connect the desired jack with the pressure supply pipe 21, whereupon pil under pressure will be delivered to the selected jack I4, l5 only. It will thus be apparent that the main hoist may be raised or lowered alone, and'that either of the jacks l4, l5 may also be raised or lowered alone, or either jack may be raised or lowered simultaneously with the main hoist.

From the foregoing detailed description it will be apparent that the several hydraulic devices may be independently operated without in any manner interfering with the operation of the others, and the single supply reservoir l1 furnishes actuating fluid for all of'the hydraulic devices. It will also be apparent that the single pump l8 supplies liquid under pressure to all of thehydraulic devices, and because of the fact that this pump I8 is supported by and oscillates with the main hoist, .the joint which is interposed between the cylinders 8 makes it possible to, utilize this common pump to so supply the fluid under pressure. .All of the oil which passes to the several hydraulically operated devices, must pass through the joint elements 23 whether this oil flows from the reservoir l1 into jacks and to the supply reservoir.

these devices, or whenreturning to the reservoir I'I. Because of the fact that the joint element 23 is mounted between the cylinders 8 in alinement withthe trunnions 20, this joint element may be maintained stationary with respect to the chassis 9, and the glands 29 cooperating with the packing 28 eifectively prevent escape of oil past the-joints. "The improved twinhoist' assemblage is relatively simple and compact in construction and has proven highly efilcient. in commercial operation, and while the specific hoist shown is of the telescopic twin cylinder type, it should be obvious thatthe invention is also applicable to other types of hydraulic hoists. By mounting the liquid supply reservoir i1 independently of the main hoist, a tank of :relatively large capacity may be utilized for supply purposes, and it will be apparent that a relatively large tank is necessary where telescopic hoists are employed. The detailed construction 'of the valves I3, 32 may obviously be varied to suit specific conditions, but the main valve 32 is preferably balanced in the manner shown in order to permit ready operation thereof. AS previously indicated, the pump i8 is of the gear type, although any other suitable type of pump maykbe employed in the improved system; and this pump may in some cases be mounted independently of the main hoist cylinders and will still permit advantageous use of the improved joint for distributing the liquid through the main cylinder ports and passages to the auxiliary The formation of the main hoist cylinders with these oil distributing ports and passages in the walls thereof and cooperating with a joint for conducting liquid to and from these passages, is an important feature of the present invention, re-

gardless of the specific disposition or.mounting @pivotally suspended cylinder and a" piston movable therein, a pump mounted upon and swingable with said cylinder, said pump being operable to deliver liquid into said cylinder tomove said piston, a liquid supply reservoir supported independently of said cylinder, means including a joint having parts relatively movable about the axis ofsuspension of said cylinder and forming 'a conduit for conducting liquid from said reservoir to said pump, and means forming a conduit.

for conducting liquid under pressure from said pump through said joint to other hydraulic devices supported independently of said cylinder. 1

2. In combination, a hydraulic hoist having a pair of laterally spaced cylinders each having a piston movable therein and. being swingable about a common axis,- a pump mounted upon and swingable with said cylinders, said pump being operable to deliver liquid into said cylinders to move said pistons, a liquid supply reservoir supported independently of said cylinders conduit means including a joint disposed bev tween said cylinders and having parts relatively movable about said-axis for conducting liquid from said reservoir to said Pump, and means forming a conduit for conducting liquid under pressure from said pump thr h Said j i to other hydraulic devices supported independently of said cylinders.

3. In combination, a twin hoist having a pair of laterally spaced parallel hydraulic cylinders each having a piston movable therein and both being swingable about a common axis at the upper ends thereof, a pump mounted directly upon said cylinders near said axis, said pump being operable to deliver liquid into both of said cylinders to simultaneously move said pistons, a liquid supply reservoir supported independently oi said cylinders, conduit means including a joint disposed between said cylinders and having fixed and movable parts relatively swingable about said axis for conducting liquid from said reservoir to said pump and from said cylinders to said reservoir, and means forming a conduit for conducting liquid under pressure from said pump through said joint to other hydraulic devices supported independently of said cylinders. 4. In combination, a hoist having a hydraulic cylinder having a movable piston therein and being swingable about an axis at the upper end thereof, a trunnion .coacting with one side of said cylinder at said axis, a liquid conducting joint having a stationary part coacting with the opposite side of said cylinder at said axis, a liquid circulating pump carried by said cylinder and communicating with the latter to deliver actuating liquid to said piston and also communicating with said joint,- a liquid supply reservoir communicating with said stationary part of said joint, and other hydraulic devices communicating with said pump and with said reservoir through said joint.

5. In combination, a twin hoist having laterally spaced hydraulic cylinders each having a piston movable therein and both being swingable about a common axis, trunnions coacting with the outer sides of said cylinders at said axis, a liquid conducting joint having a stationary part disposed between-rand coacting with the inner adjacent sides of said cylinders at said axis, a liquid circulating pump carried by said cylinders and communicating with said joint.

andwith said cylinders to deliver actuating liquid to said pistons, a liquid supply reservoir communicating with said stationary part of said joint, and other hydraulically operated .apparatus communicating with said reservoir and with said pump through said joint.

6. In combination, a twin telescopic hoist having laterally spaced hydraulic cylinders each having a movable piston therein and being swingable about a common horizontal axis, trunnions coacting with the outer sides of the upper portions of said cylinders in alinement with said axis, a liquid conducting joint having a stationary part disposed between and coacting with the inner' adjacent sides of said cylinders concentrically of said axis, packings interposed between the ends of said stationary joint part and each of said cylinders, a liquid circulating pump carried by said cylinders and communicating with said joint and ,with said cylinders to deliver liquid to said pistons, a stationary I liquid supply reservoir communicating with said stationary joint part, and a hydraulic device mounted independently of said cylinders and receiving fluid under pressure from said pump and from said reservoir through said joint.

7. In combination, a hydraulic hoist having a pivotally suspended cylinder and a movable piston therein, a pump for delivering liquid into said cylinder to move said piston, a liquid supply reservoir supported independently of said cylinder, means including a joint having parts 'relatively movable about the axis of suspension of said cylinder and forming a conduit for conducting liquid from said reservoir to said pump, and means forming a conduit for conducting liquid'under pressure from said pump through said joint to other hydraulic devices supported independently of said cylinder.

8. In combination, a hydraulic hoist having a pivotally suspended cylinder with a movable piston therein and being provided with a liquid distributing port leading to the cylinder in line with the supporting pivot thereof, a pump for delivering liquid into said cylinder to move said piston, a liquid supply reservoir, means including a joint having a stationary part communicating with said cylinder port for conducting liquid from said reservoir to said pump, and means forming a conduittor conducting liquid from said pump through said joint and away from said cylinder.

CHARLES G. EISENBERGr, JR. 

